The biochemical mechanisms by which glucagon stimulated hepatic mitochondrial function will be further studied. A microcomputer-based data acquisition system will be used in conjunction with a dual wavelength spectrophotometer for rapid scanning of glucagon-control difference spectra arising with mitochondrial suspensions in various metabolic states. Isolated segments of the mitochondrial respiratory chain will be assayed for possible hormonal effects. The mechanism of calcium efflux from isolated mitochondria and the effect of glucagon treatment on this process will be examined. Liver perfusion studies will be initiated. The isolated perfused liver system will allow the study of other hormones such as norepinephrine without complicating effects from other body tissues.